Here is (a scan of) the original slide I discovered many years ago — I think it was among a latent collection Janet unearthed. From this original, I scanned it, then cropped out a very small chunk for the photo previously posted, as you can see. (Hey, would that be Jean on the other horse?)
By the way, you can toggle between both photos by clicking on this one to enlarge its view, then using your back-and-forth keys (i.e., your arrow keys or the arrow icons).